1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to digital rights management, and more particularly, to updating meta information regarding right objects stored in a portable storage device.
2. Description of the Related Art
Recently, digital rights management (hereafter, referred to as DRM) is being actively researched and developed. Commercial services using DRM have already been implemented. DRM is useful because of the following various characteristics of digital content.
That is, unlike analog data, digital content can be copied without loss and can be easily reused, processed, and distributed, and only a small amount of cost is needed to copy and distribute the digital content. However, a large amount of cost, labor, and time are needed to produce the digital content. Thus, when the digital content is copied and distributed without permission, a producer of the digital content may lose the opportunity to profit from the digital content, and accordingly, enthusiasm for creation may be discouraged. As a result, development of the digital content business may be hampered.
There are several efforts ongoing to protect digital content. In the related art, digital content protection has been concentrated on preventing non-permitted access to digital content, and permitting only people who paid a fee to access the digital content. Thus, people who paid fees for the digital content are allowed access to unencrypted digital content, while people who did not pay fees are not allowed access. In this case, when a person who has paid for the digital content intentionally distributes the digital content to other people, however, the other people are able to use the digital content without paying any fees. To solve this program, DRM was introduced.
In DRM, anyone is allowed to freely access encoded digital content (hereafter, referred to as encrypted contents), but a license referred to as a rights object is required for decoding and executing the digital content.
Meanwhile, a portable storage device such as an XD card or a multimedia card (MMC) is a storage device that is portable and easily removable from a host device such as a mobile phone, a computer, or a digital camera. The portable storage device has various computing capabilities including data storage, operation and data control, and overcoming limitations of conventional hard disks or compact disks. Recently, a security function has been added to such portable storage devices, thereby developing a portable storage device that secures digital contents during storage and transmission, and protects copyright. The development of the portable storage device has led DRM to apply to management of ROs stored in the portable storage device. That is, the ROs are stored in the portable storage device and the host device plays back encrypted content using the ROs stored in the portable storage device.
In this case, the portable storage device may store predetermined meta information for the ROs stored by itself. The meta information is meta data indicating a status of each RO. It is often the case that meta information of the portable storage device is updated. Thus, the update of the meta information may be overhead in the portable storage device usually having less computation capacity than the host device. Therefore, a technique of reducing a data operation load of the portable storage device is desired.
Meanwhile, Korean Published Patent Application No. 2002-0020104 discloses an SRAM with a cache capability in order to increase the input and output speed of a memory card. When the memory card is combined with a digital device, the disclosed SRAM is initialized and serves as a cache storing particular data in subsequent read and write operations, thereby increasing the input and output speed of the data.
According to the disclosed technology, a separate SRAM is additionally provided in addition to a commonly used flash memory.
However, development of a method for reducing the overall operation quantity of a portable storage device while covering an increasingly advancing data input/output speed is still desired.